Increasing Strength of Recycled Materials by Fiberglass Pulverization and Powder Direct Molding

Abstract:

Direct molding is a technology where thermoset powders are agglomerated by compression molding without adding any additional substance or linking agent. It has been applied to powders from composite recycling, such as fiberglass. Agglomeration depends on residual reactivity of powders, the intrinsic re-activation of the particle surfaces because of the broken chemical links, and an incipient degradation mechanism during molding. In the case of continuous fiber laminates, the mechanical properties of the virgin item cannot be recovered as the recycled composite is made by particles. Nevertheless, high values may be reached, potentially interesting for such applications, depending on some precautions during the molding phase. Powders from grinding of fiberglass have been recovered from industry. They have been compression molded, and samples have been extracted from different parts of the molded plate to evaluate the distribution of the mechanical properties by bending tests. Results show that a bending strength up to 27 MPa can be achieved, without using any virgin material or additional substance, and a bending modulus over 3.5 GPa. However, pressure distribution during molding is not uniform and mechanical properties strongly vary from the periphery of the plate to the inner zones.

• Periodical: Materials Science Forum (Volume 1187)
• Pages: 29-36
• DOI: https://doi.org/10.4028/p-4uxRbh
• Online since: April 2026
• Authors: Fabrizio Quadrini*, Denise Bellisario, Alice Proietti, Leandro Iorio, Dounia Noqra, Giorgio Patrizii, Loredana Santo
• Keywords: Direct Molding, Fiberglass Recycling, Recycled Composites

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